Sierra Club, Chattahoochee Riverkeeper and Flint Riverkeeper filed the lawsuit last year to block the projects, arguing the Federal Energy Regulatory Commission improperly approved the projects and did not do enough to avoid impacts on low-income communities.

Dive Insight:

E&E News has the details on oral arguments this week, focused on how FERC went about approving three pipelines aimed at boosting Southeast gas supplies. According to E&E, FERC's review on environmental and climate change impacts of the pipeline projects were scrutinized by the judges.

Of almost 700 miles of new proposed pipeline, more than 80% of routes crosses near low-income and minority communities, according to lawyers from the Sierra Club. The conservation groups also say FERC did not sufficiently quantify the potential environmental impacts.

An attorney for the commission, Ross Fulton, told judges that FERC is "cognizant of the route's effects, but, as with all alternatives, the commission has to balance those choices."

Environmentalists say the pipelines will cross almost 700 bodies of water, harm 1,958 wetland systems and extend across an area that provides drinking water to approximately 10 million people. After approving the project in August, the Army Corps of Engineers added some caveats including requiring developers to purchase credits offsetting wetlands impacts.

Siting and building natural gas infrastructure has become increasingly contentious and difficult in recent years, as environmental groups push back on the need for more fossil fuels. Pipeline developers and gas power plant owners say the dispatchable plants are needed for reliability, however.

Earlier this month, the New York State Department of Environmental Conservation rejected National Fuel Gas' proposed Northern Access pipeline, a roughly-100 mile pipeline that would have moved gas from the Marcellus shale to markets in Western New York, the Midwest and Canada. That decision elicited a stern response from National Fuel President and CEO Ronald Tanski, who warned utilities in the gas-constrained region might not be able to get the fuel generators and consumers need.

"We are highly concerned about the ability of utilities in the state to meet the future energy needs of their consumers," he said in a statement.